Add chat session

bot/msg/cache.go

@@ -0,0 +1,47 @@
+package msg
+
+import (
+	"github.com/Tnze/go-mc/chat/sign"
+)
+
+type signatureCache struct {
+	signatures   [128]*sign.Signature
+	signIndexes  map[sign.Signature]int
+	cachedBuffer []*sign.Signature
+}
+
+func newSignatureCache() signatureCache {
+	return signatureCache{
+		signIndexes: make(map[sign.Signature]int),
+	}
+}
+
+func (s *signatureCache) popOrInsert(self *sign.Signature, lastSeen []sign.PackedSignature) error {
+	var tmp *sign.Signature
+	s.cachedBuffer = s.cachedBuffer[:0] // clear buffer
+	if self != nil {
+		s.cachedBuffer = append(s.cachedBuffer, self)
+	}
+	for _, v := range lastSeen {
+		if v.Signature != nil {
+			s.cachedBuffer = append(s.cachedBuffer, v.Signature)
+		} else if v.ID >= 0 && int(v.ID) < len(s.signatures) {
+			s.cachedBuffer = append(s.cachedBuffer, s.signatures[v.ID])
+		} else {
+			return InvalidChatPacket
+		}
+	}
+	for i := 0; i < len(s.cachedBuffer) && i < len(s.signatures); i++ {
+		v := s.cachedBuffer[i]
+		if i, ok := s.signIndexes[*v]; ok {
+			s.signatures[i] = nil
+		}
+		tmp, s.signatures[i] = s.signatures[i], v
+		s.signIndexes[*v] = i
+		if tmp != nil {
+			s.cachedBuffer = append(s.cachedBuffer, tmp)
+			delete(s.signIndexes, *tmp)
+		}
+	}
+	return nil
+}